The features of diagnosis and treatmentof unilateral concomitant strabismus with visual fixation defect in preschool children

BACKGROUND:Particular difficulties in treatment of children with monolateral strabismus are associated with the presence of severe amblyopia in the squinting eye in combination with a visual fixation defect (acentral or intermittent). AIM:To assess the anatomical and functional status of children with visual fixation defects, to find out the causes of failures in treatment of this group of patients, to determine the tactics of their management. MATERIALS AND METHODS:The study included 92 children of preschool age (from 3 to 7 years) with monolateral concomitant strabismus. The follow-up period for the children ranged from 12 to 72 months. The average age of the examined children was 4.6 1.1 years. Three variants of visual fixation were identified in the squinting eye: central visual fixation (CVF) 68 eyes; intermittent visual fixation (IVF ) 7 eyes; and acentral visual fixation (AVF) 17 eyes. All patients underwent a comprehensive examination: visometry; strabometry; autorefractometry; determination of the critical frequency of light flashes; assessment of visual fixation; optical coherence tomography of the retina. All children underwent passive and active pleoptics. RESULTS:The visual acuity of children with CVF significantly increased due to pleoptics. At the same time in cases of IVF and even more in those of AVF, visual acuity remained significantly lower than that of the fixating eye, pleoptics were ineffective in this group of patients. In patients with CVF, the critical frequency of light flashes of the squinting eye increased in statistically significant figures, while in IVF and AVF, the difference between squinting and fixing eye remained. According to OCT data, changes in the macular area were detected in 18 (75%) eyes in patients with IVF and AVF, which allows us to distinguish organic pathology from amblyopia. CONCLUSIONS:In children with monolateral strabismus, it is necessary to determine visual fixation of the squinting eye. At IVF and AVF, it is mandatory to conduct optical coherence tomography of the macular area to exclude organic pathology. In patients with monolateral concomitant strabismus with IVF and AVF, surgery on oculomotor muscles is indicated.

Long- and short-range bimodal signals mediate mate location and recognition in yellow fever mosquitoes

As recently reported, light flashes of incident sunlight reflecting off the wings of in-flight dipterans serve as mate recognition signals. Mate location and mate selection behavior in the yellow fever mosquito, Aedes aegypti, take place in mating swarms but the mechanisms underlying swarm formation and long-range detection of females by males remain largely unexplored. Here we show that swarm formation and mate recognition are mediated, in part, by light flash signals and wingbeat sound signals that operate at long and short range, respectively. To test for range-dependent effects of these signals, we presented ‘mating swarms’ in form of two paired 8-LED assemblies that were fitted with micro-speakers and placed either well separated in a large space or side-by-side in a small space. In the large but not the small space, the LED assembly flashing light at the wingbeat frequency of females (665 Hz), and emitting their wingbeat sound (665 Hz), attracted and prompted 5.8-times more alightings by males than the LED assembly emitting constant light and wingbeat sound. In the small space, the LED assembly flashing light and emitting wingbeat sound induced 5.0-times more alightings by males than the LED assembly flashing light without wingbeat sound. Females responded to light flash signals of males, but males failed to respond to the synthetic female pheromone component ketoisophorone added to the bimodal complex of light and sound signals. The attractiveness of light flash signals to males increased with increasing numbers of signals but did not vary according to their wavelengths (UV or blue). As predicted by the sensory drive theory, light flashes had no signal function for crepuscular house mosquitoes, Culex pipiens.

An engineered membrane-bound guanylyl cyclase with light-switchable activity

Background Microbial rhodopsins vary in their chemical properties, from light sensitive ion transport to different enzymatic activities. Recently, a novel family of two-component Cyclase (rhod)opsins (2c-Cyclop) from the green algae Chlamydomonas reinhardtii and Volvox carteri was characterized, revealing a light-inhibited guanylyl cyclase (GC) activity. More genes similar to 2c-Cyclop exist in algal genomes, but their molecular and physiological functions remained uncharacterized. Results Chlamyopsin-5 (Cop5) from C. reinhardtii is related to Cr2c-Cyclop1 (Cop6) and can be expressed in Xenopus laevis oocytes, but shows no GC activity. Here, we exchanged parts of Cop5 with the corresponding ones of Cr2c-Cyclop1. When exchanging the opsin part of Cr2c-Cyclop1 with that of Cop5, we obtained a bi-stable guanylyl cyclase (switch-Cyclop1) whose activity can be switched by short light flashes. The GC activity of switch-Cyclop1 is increased for hours by a short 380 nm illumination and switched off (20-fold decreased) by blue or green light. switch-Cyclop1 is very light-sensitive and can half-maximally be activated by ~ 150 photons/nm2 of 380 nm (~ 73 J/m2) or inhibited by ~ 40 photons/nm2 of 473 nm (~ 18 J/m2). Conclusions This engineered guanylyl cyclase is the first light-switchable enzyme for cGMP level regulation. Light-regulated cGMP production with high light-sensitivity is a promising technique for the non-invasive investigation of the effects of cGMP signaling in many different tissues.

Cerebellum size is related to fear memory and domestication of chickens

Red Junglefowl ( Gallus gallus ) were selected for divergent levels of fear of humans during eight generations, causing the selection lines to differ in fear levels as well as in the proportional brain and cerebellum masses. Birds from the two lines were then crossed to obtain an F3 intercross in order to study the correlations between brain mass and fear learning. We exposed 105 F3-animals individually to a fear habituation and memory test at 8 days of age, where the reactions to repeated light flashes were assessed on 2 consecutive days. After culling, the absolute and relative sizes of each of four brain regions were measured. Stepwise regression was used to analyse the effects of the size of each brain region on habituation and memory. There were no effects of any brain region on the habituation on day one. However, birds with a larger absolute size of cerebellum had significantly reduced reactions to the fearful stimuli on day two, indicating a better memory of the stimuli. No other regions had significant effects. We conclude that increased cerebellum size may have been important in facilitating chicken domestication, allowing them to adapt to a life with humans.

Cavezzo, the first Italian meteorite recovered by the PRISMA fireball network. Orbit, trajectory, and strewn-field

ABSTRACT Two meteorite pieces have been recovered in Italy, near the town of Cavezzo (Modena), on 2020 January 4th. The associated fireball was observed on the evening of New Year’s Day 2020 by eight all-sky cameras of the PRISMA fireball network, a partner of FRIPON. The computed trajectory had an inclination angle of approximately 68° and a velocity at infinity of 12.8 km s−1. Together with the relatively low terminal height, estimated as 21.5 km, those values were indicating the significant possibility of a meteorite dropping event, as additionally confirmed by the non-zero residual total mass. The strewn-field was computed taking into account the presence of two bright light flashes, revealing that the meteoroid had been very likely subject to fragmentation. Three days after the event, two samples, weighing 3.1 and 52.2 g, were collected as a result of a dedicated field search and thanks to the involvement of the local people. The two pieces were immediately recognized as freshly fallen fragments of meteorite. The computed orbital elements, compared with the ones of known Near-Earth Asteroids from the NEODyS database, are compatible with one asteroid only; 2013 VC10. The estimated original mass of the meteoroid, 3.5 kg, and size, approximately 13 cm, is so far the smallest among the current 35 cases in which meteorites were recovered from precise strewn-field computation thanks to observational data. This result demonstrates the effectiveness of accurate processing of fireball network data even on challenging events generated by small size meteoroids.

ON THE SECOND LIGHT FLASH EMITTED FROM A SPARK-GENERATED BUBBLE OSCILLATING IN WATER

The light emitted from the spark-generated bubbles oscillating in water is studied experimentally. Attention is paid to the emission of light from bubbles in the final stages of their first contraction and in the early stages of their following expansion. In some experiments, two close flashes of light were observed. The first light flash has already been studied in earlier works. In the present work, attention is paid to the second light flash. The relations between the first and second flashes of light and the size of the bubbles are studied and discussed in detail. It is assumed that these two light flashes are caused by two different processes taking place in the bubbles. The possible nature of these two processes is briefly discussed.

Electrical response hysteresis of crayfish photoreceptors to light intensity. Dependence on circadian time.

We studied the light-triggered current of crayfish photoreceptors. We found that when a train of light flashes of either increasing or decreasing intensity is applied, the current waveform presents the non-linear behavior known as hysteresis. Additionally, we observed that the extent of this response depends on the circadian time at which the pulses are applied. We hypothesize that positive feedback loops of biochemical networks underlying light energy transduction are responsible of the observed behavior. It has been demonstrated that a dynamical system hysteresis provides a mechanism that enhances its robustness against random perturbations. Taking into account this characteristic we hypothesize that the electrical-response hysteresis of crayfish photoreceptors: 1) makes the visual system more stable to environmental noise, and hence 2) adds stability to circadian clock oscillations.